Generating electromagnetic modes with fine tunable orbital angular momentum by planar topological circuits

Understand

Metamaterials made of periodic arrangements of electric permittivity and magnetic permeability and arrays of resonators can provide optic properties unexperienced in conventional materials, such as negative refractive index which can be used to achieve superlensing and cloaking.

• Developing new simpler structures with richer electromagnetic (EM) properties and wider working frequency bands is highly demanded for fast light-based information transfer and information processing.
• In the present work, we propose theoretically that a honeycomb-structured LC circuit with short-range textures in inductance can generate a topological photonic state accompanied by inversion between p- and d-orbital like EM modes carrying optic orbital angular momenta (OAM).
• We realize experimentally the topological photonic state in planar microstrips, a sandwich structure of bottom metallic substrate, middle dielectric film and top metallic strips with hexagonal patterns in strip width, in microwave frequency.